Fix for repeat...until scoping (#661)

tomblind · Perryvw · commit 1850e6c75a96 · 2019-07-13T18:12:41.000+02:00
fixes #657 Also added a small optimization to prevent double-negation in until-condition
diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
@@ -2216,14 +2216,17 @@ export class LuaTransformer {
     }
 
     public transformDoStatement(statement: ts.DoStatement): StatementVisitResult {
-        return tstl.createRepeatStatement(
-            tstl.createBlock(this.transformLoopBody(statement)),
-            tstl.createUnaryExpression(
-                tstl.createParenthesizedExpression(this.transformExpression(statement.expression)),
+        const body = tstl.createDoStatement(this.transformLoopBody(statement));
+        let condition = this.transformExpression(statement.expression);
+        if (tstl.isUnaryExpression(condition) && condition.operator === tstl.SyntaxKind.NotOperator) {
+            condition = condition.operand;
+        } else {
+            condition = tstl.createUnaryExpression(
+                tstl.createParenthesizedExpression(condition),
                 tstl.SyntaxKind.NotOperator
-            ),
-            statement
-        );
+            );
+        }
+        return tstl.createRepeatStatement(tstl.createBlock([body]), condition, statement);
     }
 
     public transformForStatement(statement: ts.ForStatement): StatementVisitResult {
diff --git a/test/translation/__snapshots__/transformation.spec.ts.snap b/test/translation/__snapshots__/transformation.spec.ts.snap
@@ -150,7 +150,9 @@ end"
 exports[`Transformation (do) 1`] = `
 "local e = 10
 repeat
-    e = e - 1
+    do
+        e = e - 1
+    end
 until not (e > 0)"
 `;
 
diff --git a/test/unit/loops.spec.ts b/test/unit/loops.spec.ts
@@ -981,3 +981,39 @@ test.each([
         ).message
     );
 });
+
+test("do...while", () => {
+    const code = `
+        let result = 0;
+        do {
+            ++result;
+        } while (result < 2);
+        return result;
+    `;
+    expect(util.transpileAndExecute(code)).toBe(2);
+});
+
+test("do...while scoping", () => {
+    const code = `
+        let x = 0;
+        let result = 0;
+        do {
+            let x = 1;
+            ++result;
+        } while (x === 0 && result < 2);
+        return result;
+    `;
+    expect(util.transpileAndExecute(code)).toBe(2);
+});
+
+test("do...while double-negation", () => {
+    const code = `
+        let result = 0;
+        do {
+            ++result;
+        } while (!(result >= 2));
+        return result;
+    `;
+    expect(util.transpileString(code)).not.toMatch("not");
+    expect(util.transpileAndExecute(code)).toBe(2);
+});
